Bending glass



1964 H. E. MGKELVEY EVTAL 3,162,523

BENDING GLASS Original Filed June 15, 195.6

2 Sheets-Sheet 1 INVENTORS HAEOlD M KCAVI) DAV/D fl. DO'f/ZfkT A TOR/VEYBENDING GLASS 2 Sheets-Sheet 2 Original Filed June 15, 1956 FIG. 3

F'IG.4

meow mmra MW); 19. oomuer United States ate 3,162,523 EENDENG GLASSHarold E. lvlcKelvey, Box 82, Rural Valley, Pa, and David El. Doelilert,36d Vernon St., New teasing ton, Pa.

@riginal application June 15, 1956, Ser. No. 5%,696, new Patent No.Zfidhddd, dated Sept. 1, 1959. and this application .lan. 7, 1959, Ser.No. 75,?ll6

7 (liainss. (t'll. se -ass This application relates to improvement inbending glass, and specifically refers to improvements in glass edgecontacting members used to support and guide the location of fiat glasson a hinged mold prior to bending for applying a compressive force tothe glass edge ex tremities and changing the direction of application ofthe force as the glass is bent to pinch the glass extremities againstthe upper mold shaping surface and prevent fall-ins and unwanted curlingof the glass tips.

In bending flat glass sheets into curved shapes, the sheets arepreferably first cut to size, then placed upon a skeleton type moldwhich conforms in contour to the margin of the bent glass sheet, andfinally exposed to gradually increasing temperatures until the glasssags to conform to the shape of the mold. The mold may be a singleunitary structure or composed of a number of mold sections relativelymovable with respect to each other into an open position for supportingunbent glass sheets and into a closed mold position wherein the moldsections move together to form a substantially continuous outlineconforming substantially to that desired for the margin of the bentglass both in elevation and in contour.

Molds provided with movable sections are so constructed that thesections tend to move to the closed mold position and have to be openedto receive the unbent glass sheets. According to preferred practice,sectionalized bending molds comprise a fixed center section flanked byend sections rotatable about hinges fixed relative to the centersection. The end sections are rotated into the closed mold position bymeans of counterweights carried by lever arms attached to said endsections. The weight of the unbent glass sheet keeps the end sectionsfrom closing until the glass sheet is softened by heat exposure.

When certain shapes of precut glass sheets are mounted on an open mold,it is desirable that the unbent glass extends slightly beyond the moldextremities in order to insure that the glass does not fall from itsposition of support on the mold and shatter into fragments which disruptthe operation of a bending lehr. However, if the fiat glass sheetextends beyond the edge of the mold to a distance greater than about /4;inch, the glass is marred within its viewing area when mounted in awindow frame. This marring is intensified when the weight of thesoftening glass is borne along a thin line or, in extreme cases, only apoint of contact within the marginal periphery of the glass at eachextremity of the mold. Also, the

extremities of the heat softened glass overhanging the mold extremitiestend to sag in a direction opposite from that desired. This reversesagging, once developed, cannot be eliminated by subsequent glassbending upon closing of the mold.

When a glass sheet is to be bent to severe curvatures, the difference inlength between the unbent glass sheet and the chord distance between theextremities of the sheet after bending is considerable. Occasionally,during hard usage without proper maintenance, scctionalized molds do notfunction properly, because the bearing hinges about which the endsections rotate may develop frictional resistance inhibiting freerotation. Thus, it is possible for an end section at one extremity torotate in response to the softening of the glass while the oppositeextremity fa lg is prevented from rotation because of a combination offriction and inertia. Such unequal rotation of the end sections maydisplace the glass sheet relative to the mold and result in a fall-in, acondition where the glass sheet slides off the mold.

The present invention is especially designed to prevent fall-ins fromoccurring when glass sheets are bent on sectionalizcd skeleton bendingmolds.

The present invention provides this improvement by incorporating insectionalized skeleton glass sheet bending molds glass edge contactingmembers which are pivoted relative to the end sections to provide acompressive force to opposite glass edge surfaces at opposite extremities of the glass sheet to be bent while the mold is open.

As the mold moves to its closed position, the force applied to theopposite glass edge surfaces is changed in direction so that anincreasingly larger proportion is applied in a thickness direction tothe upper corner of the edge surface initially contacted. This causesthe extremitics of the glass to be pinched against the upper shapingsurface of the mold at the mold extremities, thereby preventing slidingthat results in fall-ins.

Pinching the extremities of the glass sheet against the mold extremitiesduring the final stages of the bending cycle also inhibits the tips ofthe glass sheets from curling oil the mold tips and minimizes marking.In prior art molds of which Smith et al. Patent 2,518,951 is exemplary,tip curling has been prevented by glass contacting members which engagethe glass tips throughout substantially the entire bending cycle. Insuch molds, the glass edges are marred even when special materials areused for the glass contacting members.

In a particular apparatus especially constructed to perform the methodof the present invention, specially constructed glass edge supportingelements are attachedsecurely to a hinge rod mounted on bearing supportsfixed to each end section. Counterweighted lever arms are fixed to thehinge rod extremities and oriented in such a manner to provide a minimumrotational moment to rotate the glass edge contacting member relative tothe end section during the initial phase of the bending cycle and toincrease the moment of force causing pinching of the glass sheetextremity on the upper shaping surface of each end section's outboardextremity as the bending progresses.

This invention will be understood more clearly upon studying thefollowing description taken in conjunction with the accompanyingdrawings wherein the various reference numerals applied relate to thesame structural elements throughout the drawings. It is understood thatthe description of the particular embodiment is for purposes ofillustration rather than limitation.

in the drawings forming part of the present disclosure,

FlGURE l is a longitudinal elevation partially in perspective of atypical mold provided with a device according to the present inventionshowing the mold in the open position. 7

FIGURE 2 is a view similar to FlGURE 1 showing the mold in its closedposition.

FZGURES 3 and 4 are detailed perspective views illustrating details ofthe structural elements which are included in the present invention.

FIGURE 5 is a fragmentary sectional View of a longitudinal extremity ofa bending mold provided with glass edge supporting elements, constructedaccording to the present invention, showing in full lines the relativeposi- 'tion of a mold extremity and its pivotally attached supa relativepositions of the supporting element with respect to the mold extremityto which it is pivotally attached by superimposing in phantom theposition of the supporting element relative to the mold extremity in theclosed mold position, and assuming the mold extremity does not rotatefrom the open to'theclosed mold position.

Referring to the drawings, a mold is generally shown at M provided witha center section 26 including a pair of longitudinally extending centersection rails 22 and 24. The longitudinal extremities of the rails aredesignated 26 and 28. Beyond the outboard extremities are located endsections 30 and 32. Each of the latter is ofsubstantially U-shaped'outline and extends as a continuous rail from an outboard extremity 26of rail 22 to the laterally opposite outboard extremity 28 of rail 24.Each of the rails 22, 24, 30 and 32 is provided with an upper shapingsurface 34, 36, 38 and 40, respectively, that conforms in elevation andoutline to a portion of the margin of the bent glass sheet.

Attached to opposite inboard extremities of each end section 30 and 32are inwardly extending straps 42 and 44 respectively. These straps areprovided with downwardly extending ears 46 and 48. The ears areapertured about pivot rods 50 and 52 respectively.

Pivot rods 50 and 52 are'fixed in turn to flanges 54 and 56,respectively, which extend upwardly from opposite extremities of bracerods 58 and 64} which are used to support the mold upon a carriage (notshown). Inwardly of the pivot rods i and 52, straps 42 and 44 haveattached thereto lever arms 62 and 64, respectively. These lever armscontain counterweights 66 and 68. Stops 70 and 72 extend laterallyoutwardly from the under surface of rails 22 and 24 adjacent theirextremities in alignment with the plane of rotation of lever arms 62 and64, respectively, to provide an abutment to terminate rotation of theend sections 30 and 32 relative to the center section 20 at the properrelative orientation.

Glass edge indexing and supporting members 74 and 76 are locatedoutboard of the longitudinal extremity of each end section 30 and 32.Each of the indexing members 74 and 76 comprises a series of tabs 78extending in the plane of the bottom surface of the glass inthe openmold position alternating with a series of tabs 80 which lie in a planeangularly disposed relative to the first set oftabs. These tabs 88 areoriented parallelto the edge surfaces of the unbent glass sheets mountedon the mold for bending.

Themembers 74 and 76 are each fixed to a hinge rod 82 that is supportedat its extremities by bearing brackets 84 secured to the outer surfacesof the end sections by the outermost extremities of braces 85 extendinglongitudinally outwardly therefrom to form hinge support means. Bearingbrackets 82 and hinge rods 84 form hinge means for pivoting the glassedge indexing and supporting members 74 and 76 relative to theirrespective end mold sections 30 and 32. A U-shaped bracket 86 isattached to hinge rod 82 as by welding. The U-shaped bracket 86 includesa first leg 88 apertured to receive a set screw 9% a cross leg 92 and asecond apertured leg 94 adapted to receive a second set screw 96. Eachextremity of the rotatable hinge rod 82 extends into a lever arm 98which contains an externally threaded portion 100 upon which is mountedacounterweight M92. The position of the latter along the lever arms 98 isdetermined by the position of adjustment nuts 104.

Set screw 90 is adjusted to limit the rotation of the hinge rod 82outwardly to such an extent that the tabs 78 do not rise above the planeof the open mold defined by the rail extremities, 26 and '28 of thecenter section railsand the outboard extremity of the end sections 30and 32. This enables the flat glass sheet to be mounted in as low aposition as possible on the bending mold, a factor that has been foundto be very important in securing optimum bending of the glass sheets.Also, the tabs 80 are so disposed on the end sections that when theprecut glass sheets are loaded properly on the open mold with theindexing members 74 and 76 at their outermost positions permitted by setscrews 90, the outboard extremities of the glass sheet are equallydistant from the adjacent tabs 8% and resting either on tabs 7 8 orspaced above the latter an insignificant amount.

. By supporting the glass sheets at the extremities of the centersection rails as well as at the end section extremities, there is notendency for the unbent glass to tilt, even if the sheet has an outlinesuch that its center of gravity falls to one side of the longitudinalaxis connecting the extremities of the fiat glass sheet.

The unbent glass is loaded properly on the mold for bending as describedabove with hinge rods 82 rotated so that set screws 9tlcontact the outersurface of end sections 36 and 32. The weight of'the rigid glass keepsend sections 36 and 32 spread open. When lever arms 5 8 are released,tabs 30 apply a'minimum compressive force against the extremities of theglass sheet and no force on the upper glass surface.

As the glass is softened, the bending moments provided by thecounterweights 66 and 68 act through lever arms y 62 and64 to rotate theend sections 30 and 32 about pivot rods 50 and 52 and lift the softenedglass extremities. Theglass G slides inward relative to the end sectionrails. The lever arms 98 rotaterelative to the end sections to enablethe glass'edge contacting members 74 and 76 to follow the glass.extremities. Tabs 80, which were parallel to the glass edge 1% when themold was open, thus are free to rotate morerapidly than the endsections. This more rapid rotation establishes a component of force in athickness direction'on the upper edge corners of the glass extremities.This component of force increases with continued rotation of theindexing tabs relative to the end sections, until the component of forceis enough to pinch the upper edge corner of the glass so that the glassextremity is pinched between the tabs 8i} and the mold shaping surfaceat the outboard extremities of end sections 30 and 32, thus preventingthe glass from slipping too far inwardly at either extremity and alsoinhibiting curling of the glass tips.

Since the pinching force is applied to the upper edge corner of theglass sheet for a small portion of the bending cycle only, the glass isnot stressed in this region as much as prior art devices which requiredthe glass to be contacted throughout the entire bending cycle. Duringthe major portion of the duration of the bending cycle, the glassremains still. It is only in the last few moments of the bending cyclethat the bending occurs. Hence, glass pinching occurs for a limitedinterval only, the glass laden molds being removed from the glasssoftening temperature atmosphere as soon as the bend is completed. Lehrspeeds are adjusted accordingly to insure such prompt removal.

The present application is a division of application Serial No. 591,696,filed June 15, 1956, which has matured intoU.S. Patent No. 2,901,866 onSeptember 1, 1959.

What'is claimed is:

1. In a glass bending mold having an upper shaping surface conforming inelevation and outline to the shape desired for the margin of a bentglass sheet, the improvement comprising hinge support means secured toeach mold extremity and extending'longitudinally outwardly thereof,hinge means attached to the outermost extremity of said hinge supportmeans, a pivotable glass edge contacting member pivotably mountedto saidhinge means beyond each mold extremity to rotate relative to itsadjacent mold extremity, said glass edge contacting member includingfirst means for supporting the bottom surface of a longitudinalextremity of the glass sheet and second means angularly disposedrelative to said first means, and

means attached to said glass edge contacting member for urging saidglass edge contacting member to pivot from a first position wherein saidfirst means supports the bottom surface of an extremity of a flat glasssheet mounted on the mold for bending into a second position wherein thesecond means contacts the upper edge corner of said extremity to pinchthe glass sheet extremity against an extremity of the mold.

2. In a sectionalized glass sheet bending mold provided with sectionshavin upper shaping surfaces and each having an outer longtiudinalextremity portion, said sections being relatively movable into an openmold position in which the outer extremity portions are spread apart toreceive unbent glass sheets and relatively movable into a closed moldposition wherein the shaping surfaces provide a substantially continuousframe conforming in elevation and outline to the shape desired for themargin of the bent glass sheet, the improvement comprising a glass edgecontacting member located adjacent to and beyond the outer extremityportion of each said section, said glass contacting member includingfirst means and second means angularly disposed relative to said firstmeans, hinge means pivotally attaching each said glass edge contactingmember to its said adjacent section and a counterweighted lever armattached to each said glass edge contacting member and located inward ofsaid hinge means to apply a thrust to cause rotation of said attachedglass edge contacting member inwardly toward the mold shaping surface ofthe outer longitudinal extremity portion of said adjacent section fromone position wherein the first means supports the bottom surface of anextremity of a fiat glass sheet and the second means is out of contactwith the upper surface thereof to a second position wherein the secondmeans contacts the upper edge corner of the extremity of the glass sheetafter it is bent.

3. The improvement according to claim 2, further including stop meansoperatively connected to said glass edge contacting member for limitingthe outward rotation of said glass edge contacting member.

4. The improvement according to claim 3, further including stop meansoperatively connected to the glass edge contacting member for limitingthe inward rotation of the glass edge contacting member.

5. A sectionalized glass sheet bending mold comprising a plurality ofmold sections having upper shaping surfaces, said sections including acenter mold section and end mold sections each end mold section havingan inner extremity portion adjacent an extremity of said center mo dsection and an outer extremity portion, said end mold sections beingmovable with respect to said center mold section into an open moldposition in which their outer extremity portions are spread apart toreceive unbent glass sheets and relatively movable into a closed moldposition wherein said upper shaping surfaces provide a substantiallycontinuous frame conforming in elevation and outline to the shapedesired for the margin of the bent glass sheet, a glass edge contactingmember located adjacent to and beyond the outer extremity portion ofeach said end sections, said glass contacting member including firstmeans and second means angularly disposed relative to said first means,hinge means pivotally attaching each said glass edge contacting memberto its said adjacent section and a counterweighted lever arm attached toeach said glass edge contacting member and located inward of said hingemeans to apply a thrust to cause rotation of said attached glass edgecontacting member inwardly toward the mold shaping surface of theextremity portion of said adjacent end section from one position whereinthe first means supports the bottom surface of an extremity of a fiatglass sheet supported thereon for bending and the second means is out ofcontact with the upper surface thereof to a second position wherein thesecond means contacts the upper edge corner of the extremity of theglass sheet after bending.

6. A sectionalized mold as in claim 5, wherein said center mold sectionis of concave elevation and its longitudinal extremities closest to saidend mold sections lie in a common plane, and stop means is operativelyconnected to said glass edge contacting member for limiting the outwardrotation of said glass edge contacting member to an outward positionwherein said first means does not rise above said common plane when themold sections are moved into the spread mold position.

7. A sectionalized mold according to claim 6, wherein said centersection comprises a pair of longitudinally extending, laterally spacedshaping rails having upper edge surfaces comprising the oppositelongitudinal sides of said outline shaping surface.

References Cited in the tile of this patent UNITED STATES PATENTS682,570 Sage Sept. 10, 1901 1,999,558 Black Apr. 30, 1935 2,003,383Miller June 4, 1935 2,330,349 Galey Sept. 28, 1943 2,518,951 Smith Aug.15, 1950 2,554,572 Jendrisak May 29, 1951 2,696,476 Jend'risak Nov. 30,1954 2,827,738 McKel-vey Mar. 25, 1958 FOREIGN PATENTS 746,401 GreatBritain Mar. 14, 1956

1. IN A GLASS BENDING MOLD HAVING AN UPPER SHAPE SURFACE CONFORMING INELEVATION AND OUTLINE TO THE SHAPE DESIRED FOR THE MARGIN OF A BENTGLASS SHEET, THE IMPROVEMENT COMPRISING HINGE SUPPORT MEANS SECURED TOEACH MOLD EXTREMITY AND EXTENDING LONGITUDINALLY OUTWARDLY THEREOF,HINGE MEANS ATTACHED TO THE OUTERMOST EXTREMITY OF SAID HINGE SUPPORTMEANS, A PIVOTABLE GLASS EDGE CONTACTING MEMBER PIVOTABLY MOUNTED TOSAID HINGE MEANS BEYOND EACH MOLD EXTREMITY TO ROTATE RELATIVE TO ITSADJACENT MOLD EXTREMITY, SAID GLASS EDGE CONTACTING MEMBER INCLUDINGFIRST MEANS FOR SUPPORTING THE BOTTOM SURFACE OF A LONGITUDINALEXTREMITY OF THE GLASS SHEET AND SECOND MEANS ANGULARLY DISPOSEDRELATIVE TO SAID FIRST MEANS, AND MEANS ATTACHED TO SAID GLASS EDGECONTACTING MEMBER FOR URGING SAID GLASS EDGE CONTACTING MEMBER TO PIVOTFROM A FIRST POSITION WHEREIN SAID FIRST MEANS SUPPORTS THE BOTTOMSURFACE OF AN EXTREMITY OF A FLAT GLASS SHEET MOUNTED ON THE MOLD FORBENDING INTO A SECOND POSITION WHEREIN THE SECOND MEANS CONTACTS THEUPPER EDGE CORNER OF SAID EXTREMITY TO PINCH THE GLASS SHEET EXTREMITYAGAINST AN EXTREMITY OF THE MOLD.